VISIBLE RESTRICTED FILTER INDICATOR

摘要

A filter indicator system (10) for indicating when air flow through a filter (12) is restricted includes an indicator (26) mounted in a filter assembly (11) downstream of the filter (12). The indicator (26) includes a pop-up member (66), which includes a signal portion (72), which via a moving device (74) moves between a non-signalling position where the pop-up member (66) does not extend noticeably and a signalling position where a signal portion (72) extends noticeably. A pressure responsive releasing mechanism (82) is associated with the pop-up member (66) for initially holding the pop-up member (66) in the non-signalling position and preventing movement by the moving device (74), and for subsequently releasing the pop-up member (66) when the pressure drop across the filter (12) reaches a predetermined value.